In a manufacturing process of a semiconductor device, a process for etching a laminated film by using a mask such as a patterned resist film is repeatedly performed. For example, in a manufacturing process of a gate electrode, laminated on a semiconductor substrate in order from the bottom are a silicon oxide film or a silicon nitride film serving as a gate insulating film, a polycrystalline silicon layer serving as a gate electrode, a hard mask layer formed of silicon nitride or the like, an anti-reflection film formed of silicon oxide or the like, and a resist film. Further, the anti-reflection film and the hard mask layer are dry-etched by using the resist film patterned by employing a photolithography technique as a mask. After the resist film is removed by ashing, the polycrystalline silicon layer is etched by using the hard mask layer as a mask, thereby forming the gate electrode.
Herein, an exclusive plasma etching apparatus for etching an insulating film is used to etch the anti-reflection film and the hard mask layer, while an exclusive plasma etching apparatus for etching silicon is used to etch the polysilicon. Further, the removal of the resist film by ashing is performed by using an exclusive ashing apparatus.
On the other hand, in case of forming shallow trench isolation (STI) by forming a trench for device isolation in a silicon substrate, for example, laminated on a silicon substrate in order from the bottom are a silicon oxide film, a silicon nitride film, a silicon oxynitride (SiON) film, an oxide mask layer and a resist film. Then, the oxide mask layer, the silicon oxynitride (SiON) film, the silicon nitride film and the silicon oxide film are etched by using the resist film patterned by employing a photolithography technique as a mask. Then, the silicon substrate is etched by using the oxide mask layer, the silicon oxynitride (SiON) film and the silicon nitride film as a mask, thereby forming the trench in the silicon substrate. Also in this case, an exclusive etching apparatus for etching an insulating film is also used to etch the oxide mask layer, the silicon oxynitride (SiON) film, the silicon nitride film, and the silicon oxide film, while an exclusive etching apparatus for etching silicon is used to etch the silicon substrate. Furthermore, the removal of the resist film by ashing is performed by using an exclusive ashing apparatus.
As described above, a conventional etching process requires at least two etching steps. To be more specific, the resist pattern is first transcribed to the hard mask layer by etching the hard mask layer by using the resist film, and then the silicon substrate is etched by using the hard mask layer. This is because, in case of etching the silicon by using the resist film as a mask, a selectivity against the mask is not high enough and a high etching rate could not be obtained. Furthermore, an etching shape such as a sidewall angle or a critical dimension (CD) of the trench becomes changed depending on a pattern density of line and space, or a position on a surface of a semiconductor wafer, e.g., a central portion or a peripheral portion thereof.
Further, the gas system used for etching the insulating film differs from that used for etching the silicon, a corrosive gas is most commonly used in the silicon etching, and the etching accuracy is deteriorated by the mixing of the etching gases of the insulating film and silicon. As a result, it has been a necessary common practice to selectively use the exclusive etching apparatus for etching an insulating film and the exclusive etching apparatus for etching silicon depending upon the etching target (see, for example, Japanese Patent Laid-open Application No. H7-263415, paragraphs 0006 to 0010).